1. Field of the Invention
The present invention relates to a visual field changing method capable of easily changing and displaying a visual field to be displayed on a display screen by using an operation input part such as a mouse, a stylus pen, a touch panel or the like in a system for displaying image data, such as two-dimensional document and image, a three-dimensional virtual space, and a video of a real world captured by a camera in a predetermined display apparatus.
2. Description of the Related Art
Along with the rapid advancement of computer technology, a display object to be displayed on a screen of a display apparatus such as a display is being varied. Some display objects cannot be displayed completely within a screen of a display apparatus. In this case, a user displays a desired display content on a screen by changing a visual field.
As a visual field changing method, for example, a method used in most application software operated on a window system, such as Windows (Microsoft Corp.) and MacOS (Apple Computer, Inc.) or X-Window run on UNIX, is well-known.
According to the above-mentioned method, a scroll bar for moving a visual field upward/downward or rightward/leftward is provided at an end portion of a window screen having a rectangular region displayed on a display, and by pressing a mouse button on a slider in a scroll bar region and dragging the slider, the visual field is moved upward/downward or rightward/leftward in proportion to a drag amount, whereby a display content is updated. It is also appreciated that a zoom bar for moving a visual field forward/backward or for zooming is similarly provided.
Furthermore, when a scroll button at both ends of the scroll bar or an area between the slider and the scroll button on the scroll bar is clicked, a visual field is moved upward/downward or rightward/leftward by a predetermined amount. This also applies to the operation of a zoom bar in a similar manner. When a slider on the zoom bar is dragged or a zoom button or another area is clicked, a visual field is zoomed.
As another example, JP 2001-503896 A discloses a method for providing a plurality of visual field changing icons for changing a visual field in a three-dimensional space, which is also used often. According to this method, the respective icons provided on a screen are assigned functions, such as parallel movement of a visual field in upward/downward and rightward/leftward directions, movement in a forward/backward direction, rotation around a rotation axis in a visual field direction, rotation of a camera based on a displayed object, rotation of a camera based on a camera position, and the like. When a mouse cursor is moved to these buttons, a mouse button is pressed, and the mouse cursor is moved in any direction while the mouse button is being pressed, visual field changing determined on the button basis is performed in accordance with the movement direction and the movement amount. Regarding the movement amount, the visual field changing amount may be set proportional to the movement amount of a mouse cursor on a screen from a position where the button has been pressed, or the visual field changing speed may be set proportional to the movement amount of the mouse cursor.
Furthermore, JP 10(1998)-200807 A and JP 9(1997)-9231 A disclose a method for partitioning a window for displaying a display object into 5 (or 4) regions and assigning visual field changing processing on the partitioned region basis, instead of displaying a scroll bar, a zoom bar, an icon, and the like.
More specifically, the partitioned regions are respectively assigned upward/downward and rightward/leftward movement or zooming. When a mouse cursor is moved to the regions assigned upward, downward, leftward, and rightward movement and a mouse button is pressed, a visual field is moved at a constant speed in the assigned direction while the mouse button is being pressed. Furthermore, when a mouse cursor is moved to the region assigned zooming, and a mouse right button is pressed, a visual field is zoomed in. When a mouse cursor is moved to the region assigned zooming, and a mouse left button is pressed, a visual field is zoomed out. Partitioned lines of these regions are not necessarily displayed on a screen explicitly.
Furthermore, as represented by Adobe Acrobat Reader produced by Adobe Systems, Inc. the following method is also used often: a mouse cursor is placed at an arbitrary position in a window, and a mouse button is pressed, followed by dragging in a desired movement direction of a visual field, whereby a visual field or a display object is moved in parallel in the dragged direction. According to this method, the visual field changing amount may be set proportional to the movement amount of a mouse cursor on a screen from a position where the mouse button has been pressed, or the visual field changing amount may be set proportional to the visual field changing speed. Furthermore, another mouse button may be assigned zooming. Alternatively, by selecting an icon or a menu, the effect of mouse dragging may be switched to upward, downward, leftward and rightward movement of a visual field, zooming, tilt and pan of a camera, rotation of a camera based on an object, and the like.
However, according to the method for providing a scroll bar and a zoom bar, the display width of the scroll bar and the zoom bar is generally very small, so that a minute operation of a mouse cursor and the like are required for moving a mouse cursor on a button of the scroll bar or the zoom bar, on a handle, or on an area between the button and the handle so as to change a visual field. Therefore, such an operation is difficult for a beginner, and is not necessarily effective for an expert.
Similarly, according to the method for providing a plurality of visual field changing icons on a screen, a minute operation of moving a mouse cursor on a small icon is required. Therefore, such an operation is difficult for a beginner, and is not necessarily effective for an expert.
On the other hand, according to the method for partitioning a window for displaying a display object into a plurality of regions, and assigning visual field changing processing on the partitioned regions basis, it is required to continue to press a mouse button while the visual field is being moved upward, downward, rightward and leftward, and release the mouse button immediately when the visual field is moved to a desired position. The visual field is changed at a constant speed while the mouse button is being pressed. Therefore, in the case where it is desired to move the visual field largely, considerable amount of time is taken. Furthermore, when a visual field changing speed is set to be large so as to shorten movement time, an operation of releasing a mouse button at correct timing so as to stop changing a visual field becomes very minute, which may make it difficult to perform actual operation.
Furthermore, according to the method for using dragging, there is no particular problem in the case of changing a visual field upward, downward, rightward and leftward. However, when complicated visual field changing such as zooming and rotation of a camera is attempted, it is required to adopt another technique or switch a mode by selecting an icon or a menu. In the former case, the same problem as described above occurs. In the latter case, the procedure of changing a visual field becomes complicated, which may impair the easiness of an operation.
On the other hand, in the case of performing an operation input using a tool having no buttons such as a mouse (e.g., a touch panel, a stylus pen, etc.) as an operation input part, it becomes difficult to discriminate pointer movement from dragging. More specifically, in a touch panel, a stylus pen, and the like, it is required to move a finger or a stylus pen while keeping it in contact with an operation panel so as to move a pointer. In most systems, pressing of a mouse button is considered as the same state as that in the case where a finger and a stylus pen is brought into contact with an operation panel. More specifically, pointer movement and dragging are not discriminated from each other. Thus, in order to change a visual field using a touch panel, a stylus pen, or the like, it is required to adopt an operational method in which it is not necessary to discriminate pointer movement from dragging.